Suspended furnace roof



April 18, 1939. R. P. Hi-:UER 2,154,813

SUSPENDED FURNA-CE ROOF Filed Jan. 1934 Patented Apr. 18, 1939 PATENT OFFICE 2,154,813 SUSPENDED` FUBNACE ROOF Russell Pearce Heuer, Bryn Mawr, Pa.. assigner to General Befractorles Company, a corporation of lennlylvania Application January 18, 1934, Serial No. 707,084

v 24 Claims.

My invention relates to suspended refractory mois for furnaces and similar structures which vare subjected to high temperatures, and particularly to suspended ,roofs made from basic materials suchA as' magnesia or chrome.

A puipose of my inventionfis to reduce the amount of 4spelling which takes place in a furnace .lfoof. W

`A furtherpurpose is to provide a lateral spacer xo between bricks of, a suspended furnace roof. which will swell' after it is put in place, establish a firm contact between adjacent bricks and prevent fragments `of spalled bricks from dropping out. or, ne roof,- Y 5 .A further purpose is. to position bricks or s suspendeeiurnece roof initially rather loosely, seas togfacilitate erectionof the roof, and to subject theL bricks to a mbderate lateral thrust subsequent to erection by an increase in volume of the spacers placed between the bricks.

A further purpose is to locate spacers of an oxidizable metal between basic bricks of a suspended furnace roof, so that under flu-nace conditions ,the spacers will oxidize and therefore s permanentlyincrease in volume after construction 4if the roof, in such 'a manner that fiuxing will not take place between the bricks and the spacers because the oxide present in the bricks, 'as well as the oxide formed in the spacers, is 3'0 basic.

invention relates both to the methods involved and to the apparatus employed.

In the drawing I have shown one main form of my invention with desirable alternative forms, choosing the main and alternative forms` primarilyhfrom ,the standpoints of' convenience in illustration, satisfactory operation and easy demy onstration ofthe principles involved. Bricks for suspended roofs, are available in such a miultitude of shapes and sizes that it is obviously im.

possible to illustrate all or even most of the types Figur 1 is a vertical section of a typical suspended roof construction embodying my invention. The section is taken upon the line l--l of Figure 2.

Figure la is fragmentary section of a modiilcatio'n,.. corresponding generally to Figure 1.

'2 is a sectional top-plan view ofthe suspended roof 'shown in Figure 1.

Figure 3 is a view corresponding to Figure 1, but showing the suspendedroof after it has been exposed to furnace conditions for some time.

Figures 4 and 5 are respectively fragmentary front and side elevations of one of the bricks (Cl. 11G-99) employed in the suspended roof of Figures 1 to 3, inclusive.

Figures 6 vand '7 are respectively front and side elevations of spacers employed between the adjoining :rear faces of bricks in the-furnace construction of 'Figures l to 3, inclusive.

Figures 8 and 9 are respectively front and side elevations of spacers used between the adjoining front faces of bricks in the suspended roof of Figures 1, 2 and 3.

Figures 10 and 11 are respectively front and fragmentary side elevations of spacers used between the adjoining side faces of bricks in the' suspended roof of Figures 1 to 3, inclusive.

Figure l2 is a fragmentary front elevation of an alternative form of brick, showing a side spacer to be used with the alternative form.

Figure 12a is a fragmentary section of Figure 12 on the line |2a-l2a, showing a front spacer employed in connection with the bricks of Figures 12 and 12a.

In the. drawing similar numerals refer to corresponding parts.v

In referring to the unit used in constructing a suspended roof as a brick, I wish, of course, to include any block or similar shape, the word "brick being employed as a. convenient generic term. to cover any pre-formed refractory shape regardless of whether it is preliminarily fired, or is subjected to furnace temperature for the first time in the furnace roof.

In conventional suspended roof constructions, the bricks hang with the longest dimension generally vertical, exposing the smallest face to the furnace interior at the lbottom of the roof. The bricks placed in the roof are rather loosely associated with their neighbors. and relyfor maintaining their positions almost entirely upon the hanger attached to each brick. The whole roof structure then consists of individual bricks separatelyA supported, with little or no lateral pressure between them. Under these conditions, if a brick spall or break, fragments of the broken brick are free to drop into the furnace. 'This condition may proceed progressively until failure of the roof occurs.

By the present invention, I aim to establish contact between adjacent bricks in the furnace roof so that, if an individual brick brk or spall, the adjoining bricks may support the fragments of the broken brick and keep them from falling out of lthe roof. I secure a firm lateral support of an individual brick from adjoining* bricks without using any corrugation or similar configuration upon the faces of. the bricks.

In conventional suspended roof construction. there is considerable movement of the hotgases of the furnace between the lateral faces of adjoining bricks. It has been proposed to use high temperature cements to seal the joints between the bricks. In service, however,the bricks themselves, even though high temperature cements are used, frequently shrink and open up spaces between adjoining bricks into which. the hot furnace gases may penetrate and facilitate the destruction of the refractory roof. In the present invention I compensate for the tendency of the bricks to shrink by placing, between the lateral faces of adjoining bricks, a material which will expand in volume, thereby preventing the circulation of the hot furnace gases between the bricks.

The material used for the spacers will depend to some extent upon the temperatures involved, the costliness of material which can be employed in a given setting and the chemical character of the brick with which the spacers are to be used. In general, for a basic brick the spacers will be an oxidizable metal, preferably iron or steel. If steel be employed, it will of course be desirable to use readily corrodible steel rather than steel rendered non-corrosive by the presence of some alloying ingredient such as chromium or chromium and nickel. As an alternative to iron or steel, copper may be employed and, if the temperature be low enough, aluminum, or an alloy of aluminum and copper, may be used. Other suitable metals and alloys will serve under special conditions.

The spacers should preferably be sheet metal, and it is desirable that they should be relatively thin, as the ends exposed to the furnace temperature are more likely to melt than to oxidize if the spacers are excessively thick. I prefer to use spacers less than one-fourth (V4) inch in thickness. In practice, satisfactory spacers may be one-thirty-second (1,62), three-sixty-fourths (64) or one-eighth (Va) inch thick.

When the spacers are inserted laterally between the bricks, they will normally be in the unoxidized condition, or will have only a thin 111m of oxide such as is present on metal in the as rolled condition. After the suspended roof is constructed and the furnace is heated, the more highly heated lower ends of the spacers will oxidize first provided the furnace atmosphere is oxidizing, and, as the oxide occupies a larger volume than the original metal of the spacer, the

effect will be to apply lateral pressure upon adjoining bricks.

'I'he cumulative eiect upon the whole suspended roof will be to press the bricks tightly against one another, whereas formerly they were relatively loose laterally with respect to one another.

As the use of the suspended roof continues, more and more of the spacer will oxidize, both in thickness of oxide at any one point along the spacer, and in distance of oxidation from the lower to the upper end of the spacer. Finally, de, pending upon the temperature of the furnace, a

- condition will be reached in which the spacer at its lower end, andfor a substantial distance up from its lower end, will be completely changed into oxide, while at lpoints more remote from its lower end itwill be considerably oxidized on its side surfaces, although not completely throughout its thickness.

When the suspended roof is heated for the first time, there may or may not be some slight melting of the lower end of the spacer. Whatever the intermediate steps of the oxide formation may be, I know that after a suspended roof construction made according to my invention has been in use for some time in a lfurnace having an oxidizing atmosphere, a layer of oxide takes the place of the metal of the spacer at its lower end and for some distance above thatxpoint.

It is important that the loxide of the spacer metal be not iluxed by the material of the bricks and accordingly, bricks should be used which are basic in character. As suitable basic bricks for use in my invention I suggest magnesia or chrome (the latter sometimes considered to be aneutral refractory, although now generallyknown as a basic refractory). The bricks used should preferably be made in accordance with my U. B. Patents No. 1,851,181,1,859,512, or 1,845,968.

If the spacer be iron or steel, the iron oxide formed by oxidation of the spacer will not flux with the magnesium oxide or chromium oxide or other suitable basic oxide of the brick. Were silica brick or some other acid brick used, there would of course be fiuxingaction with the oxide formed from the spacer which would quickly remove the oxide of the spacer from its position between the bricks and render the spacer ineffective,

f In Figures 1 and 42 I show a typicalv fragment of a suspended roof structure in the form in which it will exist immediately after construction, and before the furnace has been heated. Bricks 20 having front faces 2|, rear faces 22 and side faces 23 are supported by hangers 24 engaging in recesses 25 in the bricks. The hangers are supported from any conventional overhead structure, not shown.

In the form of Figures 1 and 2, each hanger 24 has two projections 26 and 21, which extend in opposite directions, and each of which supports an individual brick. 'Ihe projections 26 rand 21 engage the downwardly directed surfaces 23 of the recesses 25 while the upwardly directed surfaces 29 of the recesses slope to provide clearance for, and permit ready insertion of, the projections 26 and 21. Each of the bricks is cut out at 3l to pass the body 3| of one of the hangers 24. The hangers 24 and the cooperating recesses in the bricks are conventional means for supporting a suspended roof.

If desired, the suspended roof may be surrounded by a permanent frame structure 32, of which only part is shown. Such a structure, Where used, confines the bricks of the roof laterally and exerts lateral pressure against adjoining bricks in the roof. The frame structure 32 as shown consists of I-beams 33 and 34 joined by a. strap 35, fastened at 36 to the respective I- beams. Such lateral supports may be eliminated if desired, and are not present in the form of Figure la. A lateral thrust on the bricks can be obtained by permanent expansion -of the spacers without the use of lateral supports, due to the tendency of the bricks to remain in vertical position under the laction of gravity and due to the tendency of the hangers to hold the bricks in position.

The spacers 31-are preferably of three types, which lit the peculiarities in shape of the respective faces of the bricks. Each ofthe spacers has a flange 3B, adapted to rest upon the upper corner of a brick as at 39 or against the flange of another spacer as at 40, and to prevent the spacer from dropping from its position between the bricks before oxidation holds the spacer in place. The flanges 38. while serving a desirable function.

in preventing the spacers from dropping out of position. may be dispensed with, and this function may be performed in any other suitable way.

In Figures Sand 7 I illustrate a spacer 4l for use between the rear faces of bricks. It corre sponds generally in size with the rear faces 22 of the bricks. In Figures 8 and 9 I show a spacer 42, of the same general size as the 'spacer 4I, for use between the front faces 2| of the bricks. The spacer 42 is cut away at 43 to permit ready insertion of the hanger 24. In Figures l and l1 I show a spacer 44 for use between the side faces 23 of the bricks.

It' will be evident that the sizes and contours of the spacers will depend very largely upon the sizes' and contours of the faces of the bricks and that, while it is desirable to have the spacers conform more or less exactly to the external outlines of the faces of the bricks, the spacers may, if desired, diifer from the external outlines of the bricks faces. It will also be evident that, while I show spacers in Figures 1 and 2 in contact with all four faces of the bricks (with the exception of the outermost bricks), some advantage may be obtained from the invention by using spacers between some but not all of the adjoining faces of the bricks.

The hanger and spacer functions may be combined in a single fitting, suitably consisting of a hanger and a spacer rigidly connected, as shown in Figure 1a, in which the spacers 42' are suitably secured, as by welding at 50, to the hangers 24. In this construction the spacers 42' are supported directly by the hangers. If desired, the spacer may carry any suitable hanger means, and

may be held from above in any suitable way.

In Figure 3 I illustrate a suspended roof after it has been subjected to furnace temperature for some time. The lower ends 45 of the spacers 31 are completely converted into oxide, with corresponding increase in volume, as indicated somewhat imperfectly upon the drawing. The portion of the spacers above the lower ends 45, as for example at 46, are partially converted into oxide, with correspondingly less, but nevertheless marked, increase in volume. The upper portions of the spacers at 41 have not yet become very extensively oxidizedMThe effect of the oxidation upon the suspended' roof is to force any two bricks adjoining a given spacer apart. Some of the oxide under the pressures developed appears to penetrate small roughnesses and cavities in the surfaces of the bricks, thus producing a firm interlocking between the oxidized spacer and the brick. The resultant suspended roof consists of contact with adjoining faces of the bricks.

"inserted, In Figure 12 I show a spacer 48 on one side of the brick, and in Figure 12a I show a spacer 49 applied valso to the front of the brick.

Many variations of hanger may be used, and

I do not in any sense confine the application of my spacers to cases where any particular type of hanger is employed, or even where any hanger is employed.

As the spacers act by exerting lateral pressure upon the bricks, it is importantthat the spacers be within themselves laterally incompressible. In

other words, it would be undesirable to employ a spacer which could collapse -under pressure or yield toward the interior from its outside faces. If the lateral space between bricks is not substantially filled by the spacer before the spacer increases in volume, increase in volume of the spacer will be ineffective to exert lateral pressure on the bricks, as the increase in volume will merely fill free space between the bricks. It is therefore important that the spacer (or something unyielding) substantially fill the space between bricks in the first place.

While I prefer to use a material which will increase in volume due to oxidation. I may use a spacer which from any cause, as for example from some other chemical reaction than oxidation, permanently increases its volume after it is inserted in the suspended roof. In such a case,

so as not to destroy the effectiveness of the spacer.

It will be evident that the oxidation of the spacer is really the last step in constructing the roof, as the roof is not complete until the spacer increases in volume.

It has been proposed to interpose metallic members between bricks of continuous arch (as distinguished from suspended) roofs, which are sprung from skewbacks and kept in place against the force of gravity by the compressive thrust exerted on the brick by such skewbacks. My invention is accordingly directed to suspended roofs in which a mild lateral pressure upon the bricks may be usefully applied and seeks to provide this mild pressure without resort to the excessive pressures which arise in arched roofs and skewback construction. It is well known that with basic brick these high pressures in arched roof construction cause shearing or spailing of the brick with resultant failure of the roof.

In view of my invention and disclosure variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of my invention without copying the structure shown, and I, therefore, claim all such in so far as they fall within the reasonable spirit and scope of my invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

l. The method of constructing a long-lived suspended roof from basic refractory bricks, which consists in hanging from above individual preformed basic refractory bricks, in interposing between the lateral faces of the bricks an oxidizable metal which increases its volume on oxidizing, thick enough before the roof is heated to substantially fill the space from one brick to another throughout a major portion of said space and in heating the metal in an oxidizing atmosphere to cause it to increase in volume by oxidation.

2. 'I'he method of constructing a. long lived suspended roof from basic refractory bricks. which consists in hanging from'above individual preformed basic refractory bricks one beside another, in interposing a metal sheet containing iron g between adjoining faces of the bricks, which sheet .26. the chemical character of the brick will be chosen firmly fills the space from one brick' to another before the roof is heated, and in heating theroof to a high temperature under oxidizing conditions, whereby the iron is oxidized. increases in volume, and holds the bricks firmly in place.

3. The method of constructing a long-lived suspended roof from basic refractory bricks, which consists in hanging from above individual preformed basic refractory bricks one beside another, in interposing a metal sheet containing copper between adjoining faces of the bricks, which sheet nrmly fills the space from one brick to another before the Iroof is heated, and in heating the roof to a high temperature, under oxidizing conditions, whereby the copper is oxidized, increases in volume, and holds the bricks firmly in place.

4. The method of constructing a long-lived suspended roof` from basic refractory bricks, which consists in hanging from above individual preformed basic refractory bricks one beside another, in interposing a metal sheet containing aluminum between adjoining faces of the bricks before the roof is heated, which sheet firmly iills the space from one brick to another before the roof is heated, and in heating the roof to a high temperature under oxidizing conditions, whereby the aluminum is oxidized, increases in volume, and holds the-.bricks firmly in place.

5. In a suspended furnace roof, a plurality of preformed basic refractory bricks arranged side by side, means for suspending the individual bricks. and laterally incompressible metallic spacers between the bricks, said spacers increasing in over-all thickness permanently under application of heat and thereby holding the bricks laterally nrm. 1

6. In a suspended furnace roof, a plurality of preformed basic refractory bricks arranged with their greatest dimension vertical, hangers cooperatively engaging and supporting individual bricks, and spacers substantially occupying the entire spaces between adjoining faces of the bricks and comprising an oxidizable metal.

7. In a suspended furnace roof, a plurality of basic refractory bricks arranged side by side, hangers cooperatively engaging and supporting the bricks, a plurality of laterally incompressible metallic spacers between the adjoining lateral faces of the bricks Vand means for holding the spacers against displacement from between adjoining bricks, whereby the spacers will oxidize and hold the bricks in place.

8. In a suspended furnace roof, a plurality of basic refractory bricks arranged side by side, means for suspending the individual bricks, laterally incompressible sheet metal spacers containing iron occupying the space between adjoining faces of the bricks, and means for preventing the spacers from displacement by downward move'- ment from their positions between the bricks.

9. In a suspended furnace roof, a plurality of basic refractory bricks arranged side by side, means for suspending the individual bricks, laterally incompressible sheet metal spacers containing copper occupying the space between adjoining faces of the bricks, and means for preventing the spacers fmm displacement by downward movement from their positions between the bricks.

10. In a suspended furnace roof, a plurality of basic refractory bricks arranged side by side, means for suspending the individual bricks, laterally incompressible sheet metal spacers containing aluminum occupying the space between the adjoining faces of the bricks, and means for preventing the spacers from displacement by downward movement from their pomtions between the bricks.

11. In a suspended furnace roof, a plurality of preformed basic refractory bricks side by side, having their long dimensions vertical, hangers cooperatively engaging and supporting the bricks, and spacers, each comprising a single thickness of oxidizable metal,extending 'between and in loose engagement withl adjoining faces of the bricks before the roof is heated.

12. In a suspended furnace roof, a plurality of basic refractory bricks side by side, having their long dimensions vertical and having recesses near their upper ends, hangers extending into the recesses and supporting the bricks. and spacers, each comprising a single thickness of oxidizable metal, extending between and in loose engagement with adjoining faces of the bricks and flanged at their upper ends to support the spacers when they engage the bricks but loosely.

13. In a suspended furnace roof, a plurality of preformed basic refractory bricks side by side. and fittings comprising hanger portions cooperatively engaging and supporting the bricks, and spacer portions of oxidizable metal connected to the hanger portions and substantially completely filling the spaces between certain adjoining faces of the bricks before the roof is heated.

14. The method of constructing a suspended furnace roof from unburned basic refractory bricks, which consists in hanging from above individual preformed unburned basic refractory bricks one beside another,- in interposing between the lateral faces of the bricks an oxidizable metal which increases its volume on oxidizing, thick enough before the roof is heated to substantially i111 the space from one brick to another throughout a major portion of said space, in heating the bricks during use in the` roof, thereby causing them to shrink, and in concurrently oxidizing the filling to cause it to increase in thickness permanently as the bricks shrink, thereby maintaining the continuity of the roo 15. In a suspended furnace roof, a plurality of initially unburned preformed basic refractory bricks side by side, means for suspending the individual bricks, and laterally incompressible sheet metal spacers occupying the space between adjoining faces of the bricks before the roof is sus- `jected to ring temperature, said initially unburned bricks shrinking when flrst subjected to firing temperature and said spacers increasing. in thickness when subjected to firing temperature and compensating for the shrinkage.

16. Furnace roof construction comprising supports, non-acidic refractory bricks suspended thereon by their upper ends and arranged in lateral association with one another, and ferrous metallic plates supported at their upper end portions and arranged between and in contact with lateral surfaces of adjacent bricks and having some of their material coalesced with v some of the material of the lower portions of bricks which they contact.

17. Furnace roof construction comprising supports, magnesite refractory bricks suspended thereon by their upper ends and arranged in initially rather loose lateral association with one another, and laterally incompressible ferrous sheet metal plates supported from the bricks, and each arranged between and having its opposite surfaces in contact with lateral surfaces of adjacent bricks. said spacers oxidizing and holding the bricks in place.

' 18. Furnace roo! construction as specified in claim 17 and wherein respective plates contact both opposite and adjacent faces of a brick.

19. Furnace roof construction' as speciiied in claim 17 and wherein said plates have retentive engagement at their upper ends with the bricks and support from the bricks.

20. Furnace root construction as speciiied in claim 17 and wherein the several bricks hang approximately phnnb.

21. Furnace roof construction as specined in claim 17 and wherein the bricks and plates, after assembly and prior to prolonged heating o! the root, are throughout relatively loose laterally with respect to one another.

22. Furnace roof construction comprising basic bricks suspended by their upper ends in lateral 20 juxtaposition to one another. and `oxidilsable sheet-metil Plll WOM 0n the bricks and arranged between juxtaposed bricks and having portions toward their lower ends coalesced therewith.

23. Furnace rooi construction as specified in claim 16 and wherein the brick contain a substantial proportion ot magnesite.

24. In furnace roof construction,vin combination, a plurality of magnesite bricks each having a support-engaging portion at one end. supporting means engaged with said supportengaging portions and holding the bricks suspended in juxtaposed association with one another, and laterally incompressible sheet iron plates supported at their upper ends and arranged between and in contact with the juxtaposed bricks, all plates in contact with the same brick being free from one another and the bricks being initially loose with respect to one another, said spacers oxidizing and holding the bricks in place.

RUSBEILPEARCEHEUER. 

